Rockwell Automation T3420AF ICS Regent Analog Input Modules - Manual (Page 12)

Analog Input Modules (T3420A, AF)
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Industrial Control Services
Simplex Configuration
Analog input modules provide a suitable interface to non-
critical input signals. Although many of the circuits in the
analog input modules are automatically tested and
annunciated, some logic circuits and all of the field-side
sensing circuits are simplex and non-tested. This simplex
input configuration is illustrated in Figure 5.
Figure 5. Simplex Analog Input Configuration.
Fault Tolerant Configurations
For critical inputs, redundant input modules are used in a
2oo3 or 1oo2 fault tolerant configuration. In these
configurations the redundant input modules are connected to
single or multiple sensors. If redundant sensors are installed
in the field, the redundant modules are connected so that each
sensor connects to one of the redundant modules. These
configurations are illustrated in Figure 6, showing triple
redundant input modules. Each analog input module is hot
replaceable. In redundant input configurations, if a fault
occurs on one module, it can be removed and replaced while
the system continues to sense the inputs from the remaining
two input modules.